1. Field of the Invention
The present invention relates to a device and method for detecting, measuring, and recording at a selected site the intensity of radiation striking the site which reduces within the spectrum which corresponds to a green plant's known photoactive spectrum, and then, based on the recording, alphanumerically and graphically displaying the photoactive radiation exposure incident at the site during a particular portion of a day, the entire day, week, or month. The photoactive radiation information thus provided enables gardeners, farmers, researchers and others to match the types of trees, shrubs, crops or other plants that grow best under particular radiation conditions with sites having such radiation conditions over desired, extended periods of time.
2. Description of the Related Art
Whether a particular garden, agricultural, exterior or interior site will be exposed to the appropriate amount of radiation is a common question. Like animals, plants occupy specific ecological niches. Plants that are well suited or matched to the lighting intensity usually incident upon the garden in which they grow will grow to their full potential, assuming other plant growth requirements such as the appropriate nutrients and moisture are also present.
The current home gardening industry rates plant light requirements in general terms. Typical terminology used to describe plant light requirements includes such terms as full sun, part sun, and shade. Most often, home gardeners determine a plant's light requirements by guessing whether the light striking their home garden plot is full or part sun, or shade. Often, home gardeners guess incorrectly because they have little sense of the degree of light exposure at a site that has some degree of shading, and as a result the plants selected for a particular site grow poorly or die.
In addition, gardeners frequently ignore the fact that the radiation best for optimum growth for plants (later referred to as plant-active radiation spectrum) is photoactive radiation within the spectrum of approximately 400-750 nm. Also to be recognized is that plants do not use ultraviolet (UV) radiation of approximately 200-400 nm for photosynthesis. In other words, traditional practice ignores the effect of the wavelength content of incident radiation on plant growth. This can be particularly misleading in artificial lighting conditions, where a substantial portion of the wavelengths emitted from the lighting falls outside the photoactive spectrum of 400-750 nm.
Professional growers sometimes depend on light meters that measure instantaneous light intensity over the full light spectrum, either in foot-candles or lux. The professional grower is experienced and has the resources to take numerous readings over time to determine the light usually incident upon a particular site, and may use the information to apply more, less, and/or different artificial lights or to increase shading of the plants. For the home grower, whose light conditions are likely to change dramatically depending on the sun's position in the sky, there has been no device available to record a site's light conditions during different parts of the day and over extended periods of time during a day, week, or month. For a home gardener, and even professionals, taking careful readings over time to determine the instantaneous light intensity usually incident upon a particular site is cumbersome and, thus, unlikely to be started or completed. Furthermore, such readings (in foot-candles or lux) are not particularly relevant to home-gardeners purchasing plants that are merely labeled, full sun, part sun, or shade plants.
Photographers use light meters that detect, measure, and display the instantaneous light radiation intensity at a particular site at a particular time. In addition, there are light meters that measure human exposure to potentially harmful ultraviolet (UV) radiation. A sunburn meter of this type is described in U.S. Pat. No. 4,975,584 issued to Benjamin et al. ("the '584 Patent"). The device disclosed in the '584 Patent comprises a series of stations at selected sites and means for detecting radiation and producing machine-readable signals corresponding to the level of radiation detected at each site. It also incorporates a plurality of sensing stations for transmitting data signals to a central station that processes the data and sends the processed signal to display stations. The device of the '584 patent also employs a display station for processing the signals and display a reading corresponding to the intensity of UV radiation at the station to the public. This device, however, merely informs individuals about the intensity of UV radiation occurring at a particular site at a particular time.
Another personal UV radiometer is described in U.S. Pat. No. 5,008,548 ("the '548 Patent"). The device described in the '548 Patent determines the direction of highest intensity of incident radiation and determines the amount of the incident radiation or dosage. The device of the '548 Patent displays the dosage detected in common engineering units, typically milli-Joules per square centimeter. It also incorporates an alarm that may be actuated upon attainment of a predetermined dosage level set by the user.
U.S. Pat. No. 5,306,917 ("the '917 Patent") discloses an UV radiation detector device intended for medical use. The '917 Patent comprises a sensor unit for detecting UV radiation and transmitting signals corresponding to the intensity of the UV radiation in the device's memory. However, when the device of U.S. Patent '917 is located in the shade, intensity signals will be equal to zero. Therefore, zero signals in this device will not be memorized, in an effort to measure only medically risky radiation levels.
All of the above prior art devices measure intensity of UV radiation accruing at a particular site at a particular time. None of the UV radiation sensors measures photoactive radiation for display of daily, weekly, and monthly photoactive radiation exposure data particular to a specific garden site. Further, none of the prior art devices provide a light filter system that selectively and proportionally attenuates the intensity of incident radiation wavelengths transmitted to a light sensor that have a sub-optimum effect on plant growth.
Therefore, it is one object of this invention to measure, record, and display the intensity of radiation falling within a selected plant's photoactive radiation spectrum and striking a particular site at a particular time and over a specified time period.
A further object of the invention is to provide a light filter system that selectively transmits to a light sensor incident radiation wavelengths of the protective radiation spectrum that have an optimum effect on plant growth.
Another object of the present invention is to provide a light filter system that selectively and proportionally attenuates the intensity of incident radiation wavelengths transmitted to a light sensor that have a sub-optimum effect on plant growth.
It is another object of this invention to provide a method and device for determining the photoactive radiation incident on a particular site in user friendly radiation units identified and labelled by the present invention as "sols."
A further object of this invention is to provide a user's guide, and labels for use in connection with plant products, that describe photoactive light requirements for particular plants in sols.
Other advantages and features of the invention will become apparent from a consideration of the ensuing description and drawings.